Refactor into init_labels

app/assets/javascripts/init_labels.js

+import LabelManager from './label_manager';
+import GroupLabelSubscription from './group_label_subscription';
+import ProjectLabelSubscription from './project_label_subscription';
+
+export default () => {
+  if ($('.prioritized-labels').length) {
+    new LabelManager(); // eslint-disable-line no-new
+  }
+  $('.label-subscription').each((i, el) => {
+    const $el = $(el);
+
+    if ($el.find('.dropdown-group-label').length) {
+      new GroupLabelSubscription($el); // eslint-disable-line no-new
+    } else {
+      new ProjectLabelSubscription($el); // eslint-disable-line no-new
+    }
+  });
+};

app/assets/javascripts/pages/projects/labels/index/index.js

-import LabelManager from '~/label_manager';
-import GroupLabelSubscription from '~/group_label_subscription';
-import ProjectLabelSubscription from '~/project_label_subscription';
+import initLabels from '~/init_labels';
 
-export default () => {
-  if ($('.prioritized-labels').length) {
-    new LabelManager(); // eslint-disable-line no-new
-  }
-  $('.label-subscription').each((i, el) => {
-    const $el = $(el);
-
-    if ($el.find('.dropdown-group-label').length) {
-      new GroupLabelSubscription($el); // eslint-disable-line no-new
-    } else {
-      new ProjectLabelSubscription($el); // eslint-disable-line no-new
-    }
-  });
-};
+export default initLabels;